Pressure relief valve

ABSTRACT

A PRESSURE RELIEF VALVE FOR AEROSOL CANS COMPRISING A STEM PORTION AND A HEAD PORTION, A STEPPED SPRING ON SAID STEM PORTION, A WASHER BETWEEN SAID HEAD PORTION AND THE STEPPED SPRING. THE STEPPED SPRING BEING UTILIZED TO THREADABLY ENGAGE A HOLE IN SAID AEROSOL CAN UNTIL THE STEM IS COMPLETELY INSIDE OF SAID CAN PLACING SAID WASHER ADJACENT THE OUTSIDE OF SAID CAN BETWEEN SAID CAN WALL AND THE HEAD, THEN THE STEPPED SPRING ACTING TO CAUSE A COMPLETE CLOSURE BETWEEN THE CAN WALL AND THE WASHER. ON INCREASE IN INTERNAL PRESSURE IN THE CAN THE STEM WILL MOVE OUTWARDLY TO EXPAND THIS ASSEMBLY, THUS SLOWLY VENTING EXCESS PRESSURE.

Feb. 6, 1973 c. H. BENTLEY 3,714

PRESSURE RELIEF VALVE.

Filed March 24, 1971 INVENTOR. CZAENCE H. 315N746) United States Patent 3,714,965 PRESSURE RELIEF VALVE Clarence H. Bentley, Los Angeles, Calif., assignor to Delbert John Bentley, Albert Byron Bentley, Douglas Rodney Bentley, and David Alan Bentley, fractional part interest to each Filed Mar. 24, 1971, Ser. No. 127,734 Int. Cl. F16k 17/04 US. Cl. 137-541 Claims ABSTRACT OF THE DISCLOSURE A pressure relief valve for aerosol cans comprising a stem portion and a head portion, a stepped spring on said stem portion, a washer between said head portion and the stepped spring. The stepped spring being utilized to threadably engage a hole in said aerosol can until the stem is completely inside of said can placing said washer adjacent the outside of said can between said can wall and the head, then the stepped spring acting to cause a complete closure between the can wall and the washer. 0n increase in internal pressure in the can the stem will move outwardly to expand this assembly, thus slowly venting excess pressure.

BACKGROUND OF THE INVENTION The present invention relates to safety valves for aerosol cans and the like. In the manufacture and use of aerosol cans it frequently occurs that the internal pressure is raised to a dangerous point by heat or overfilling which causes the can to explode. This situation can be extremely dangerous when the container, with its contents under pressure, is filled with a highly 'volatile substance such as lacquers, butane or the like. Also there is a problem in disposing of these containers when they become empty in that some of the contents almost always remain in the can; or the dispensing valve has become inoperative prior to the dispensing of all of the contents of the can.

The present invention alleviates these problems by providing a simple three piece construction which may be threadably inserted in a small hole in the can prior to or after filling of the can which will slowly bleed off any excess internal pressure as it rises. The present invention in its preferred embodiment places this reilef valve above the contents in the can so as to bleed off the inert propellant in the can and thus prevent unwanted escape of the contents. If the contents of the can are also above the devised pressure then they also would be bled oif at a gradual rate. It should, however, be noted at this point that this relief valve may be placed at any point on the can including the bottom.

The present attempts to alleviate this problem have all been centered around making seams that will split and spill the contents more or less completely or supplying complicated valve mechanisms with the head or nozzle portion of the can.

OBJECT OF THE INVENTION It is therefore a principal object of the present invention to provide a relief valve which will prevent explosion of aerosol cans due to overheating or overfilling.

A further object of this invention is to provide a valve with a minimum number of parts.

Another object of the present invention is to provide a safety valve which will vent excessive pressure without substantial loss of the contents of the can or gradually reduce the contents of the can until a safe pressure level is attained.

A still further object of the invention is to provide a valve that is easy to assemble into the aerosol can which cannot be readily removed after assembly.

3,714,965 Patented Feb. 6, 1973 These and other objects and advantages of the present invention will become apparent from the following description taken in view of the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional elevation of the relief valve in an assembled configuration prior to the insertion in an aerosol can.

FIG. 2 is a cross-sectional elevation taken through lines 2-2 of FIG. 5.

FIG. 3 is a side elevation of the relief valve of the present invention partially inserted in the wall of an aerosol can.

FIG. 4 is an exploded elevation illustrating the various components of the relief valve.

FIG. 5 is a side elevation of an aerosol can illustrating a location of the relief valve.

DESCRIPTION OF THE INVENTION Referring now to FIG. 1 which illustrates an assembled relief valve prior to the insertion into the can the valve comprises a stem portion 10 and a head portion 12. Attached to the stem is a stepped spring having a variation of diameters which act as a tapered thread at this stage of assembly.

Beneath the head 12 is an elastic washer 16 which, when assembled in the aerosol can of FIG. 5 acts as a seal between the wall 28 of the can and the head 12 to act as a seal therebetween. To prevent the stepped spring 14 from resting on the washer 16 a small shoulder 18 is provided.

The principal objects of the invention may be performed without this shoulder but it is preferable to provide this shoulder 18 in order to preserve the shelf life of the valve by preserving the integrity of the washer in that if the stepped spring 14 was to rest on washer 16 for a long period of time the washer would take a set and subsequently not provide an adequate seal between the can wall and the head 12. Shoulder 18 could also be eliminated and the spring 14 could be caused to rest on shoulder 19 accomplishing a similar result.

The top head 12 is provided with a key-way 20 which may be of any suitable type ranging from a simple screwdriver slot to one requiring some exotic type of tooling. This slot is used to rotate the valve at a slight angle as illustrated by FIG. 3 into a threaded engagement into a hole 22 in the can wall until all of the stepped spring 14 has been driven into the can as illustrated in FIG. 2.

At this point the stepped spring 14 no longer acts as a screw thread but performs its intended function as a stepped spring and seals the washer 16 between the can wall 24 and head 12.

When the pressure in the can, designated generally as 28, increases above a predetermined safe level, the pressure is exerted on the area inside seal of the valve comprising stepped spring 14 and breaking the seal between the wall 24 and the washer 1'6 venting the excess pressure without a substantial loss of the contents of the can. When the excess pressure of the can is vented the washer returns to its normal closed configuration.

Various changes and modifications may be made in carrying out the present invention without departing from the scope and spirit thereof; insofar as these changes and modifications are within the purview of the appended claims, they are to be considered as part of the invention.

I claim:

1. A pressure relief valve for insertion into a hole in a pressure vessel, comprising:

a stem member dimensioned for insertion into said hole,

having a head member of greater diameter than said hole integrally attached to one end;

a stepped helical spring member surrounding said stem member, having a first end spaced from said head member, which first end is dimensioned to be received by said hole and is secured against rotation and slippage to said stem member, and having a second end nearest said head member of greater diameter than said hole;

said second end adapted on rotation of said head and stem members to pass through said hole and bear against the margin thereof within said pressure vessel, to urge said head toward the margin of said hole outside said pressure vessel;

and an elastic gasket member interposed between said head member and said spring member, which gasket member upon insertion of said pressure relief valve into said hole provides a seal between the wall of said pressure vessel and said head member adapted to open should the pressure inside said vessel exceed a predetermined pressure.

2. The pressure relief valve of claim 1, wherein means are provided for arresting the tension of said spring member away from said elastic gasket member to prevent said elastic gasket member from becoming permanently distorted by said spring member resting on said gasket member prior to insertion of said valve into said vessel.

3. The pressure relief valve of claim 1, wherein:

below said head portion a tapered portion is provided on said stem portion;

said tapered portion arresting said spring member to prevent said spring member from resting on said gasket member prior to insertion of said valve into said vessel.

4. The pressure relief valve of claim 1, wherein: said second end of said spring member passes into said vessel in the manner of a screw thread; and said spring member functions as a tension member after all portions thereof have been driven into said vessel. 5. The pressure relief valve of claim 1, wherein said stem member comprises:

References Cited UNITED STATES PATENTS 3,267,959 8/1966 Savage l3754l X 2,168,297 8/1939 Voke 22 2-496 2,609,975 9/ 1952 Senger 222-496 2,619,316 11/1952 Wilson 137-541 3,227,175 1/1966 Remington et al. 251-303 30 ROBERT G. NILSON, Primary Examiner US. Cl. X.R. 

